1. Field of the Invention
The present invention relates to a combustion-engined setting tool for driving fastening elements such as nails, bolts, pins, and the like in a constructional component and including a combustion chamber for combusting therein a fuel gas-oxidant mixture and having an axially displaceable wall, a guide cylinder adjoining the combustion chamber, and a setting piston displaceably arranged in the guide cylinder.
2. Description of the Prior Art
Setting tools of the type described above can be driven by gaseous fuels or liquid fuels which are evaporated before combustion. The setting energy for driving in a fastening element is obtained by combustion of a fuel-air mixture in a combustion chamber and is transmitted to the fastening element by the setting piston.
German patent DE 40 32 202 C2, from which the present invention proceeds discloses a setting tool of the type described above and in which a guide cylinder for a setting piston is at least partially displaceable in a combustion chamber casing. The combustion space of the combustion chamber is divided in at least two chambers. The two chambers are separated from each other by at least one displaceable intermediate wall or separation plate and are limited by a second, displaceable rear wall. For removal of flue gases from the combustion chamber, the second and intermediate walls are displaced toward a combustion chamber wall adjacent to the setting piston, with a very small remaining space, whereby the flue gas is forced out of the combustion chamber. When the chambers are expanded again, upon the setting tool being pressed again against a constructional component, the chambers and, thereby, the combustion space are again filled with fresh air. The walls are displaced by several, displaceable relative to the combustion chamber, guide rods.
The drawbacks of the known setting tool consists in that the use of several guide rods for displacing the displaceable walls is associated with large expenses and, on the other hand, can lead to jamming of the displaceable mechanism when the clearances are not precisely formed at the elements of the displaceable mechanism are produced with an inadequate precision.
Accordingly, an object of the present invention is to produce a setting tool of the type described above in which the foregoing drawbacks of the known setting tool are eliminated.